docs(el3-runtimes): context management refactor proposal

This patch submits an RFC to refactor the context management
mechanism in TF-A.

Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: Ia1ad5a85cb86c129e2feaf36bed123f0067c3965
diff --git a/docs/design_documents/index.rst b/docs/design_documents/index.rst
index c82d2ee..257a510 100644
--- a/docs/design_documents/index.rst
+++ b/docs/design_documents/index.rst
@@ -7,6 +7,7 @@
    :numbered:
 
    cmake_framework
+   context_mgmt_rework
    measured_boot_poc
 
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